EP 0 727 135 A describes a combine, in which the straw is laid down on the ground in a swath by straw walkers via a guide plate in a swath laying mode or fed to a straw chopper in a chopping mode, in which the straw is chopped and distributed on the field. The guide plate can be moved into a third position, in which the straw as well as the chaff can be conveyed through the straw chopper. The chaff is pneumatically conveyed into the straw chopper by means of blowers of the cleaning assembly.
WO 01/01754 A describes a combine with a straw chopper and a chaff spreader. The chaff spreader is able to throw the chaff into the straw upstream of the straw chopper such that it moves through the straw chopper together with the straw and is distributed on the field approximately over the operating width of the cutting mechanism. It is also possible to distribute the chaff over the operating width by means of the chaff spreader. In this case, the chaff is not moved through the straw chopper while the straw is chopped in the straw chopper and distributed on the field. If the straw is not chopped but rather conveyed around the front side of the straw chopper by a pivoted straw guide plate and laid down on the field, the chaff can be distributed on the field over the operating width of the cutting mechanism or blown into the straw swath.
WO 02/34029 A proposes a different chaff spreader arrangement. This chaff spreader is able to blow the chaff directly against straw guide plates arranged downstream of the straw chopper such that the chopped straw and the chaff are distributed over the operating width via the guide plates. In another operating mode, the straw is conveyed around the rear of the straw chopper and laid down on the field in the form of a swath, wherein the chaff is conveyed along the straw guide plates by the chaff spreader and distributed on the field over the operating width to both sides of the swath. In other operating modes, the straw is chopped by the straw chopper and distributed over the operating width or laid down in the form of a swath while the chaff is distributed by the chaff spreader over the operating width to both sides of the swath. In this arrangement, it is also possible to blow the chaff into the straw swath in the swath laying mode.
DE 100 64 356 A proposes to always convey the chaff through the straw chopper while the straw is either conveyed through the straw chopper in the chopping mode or around the rear side of the straw chopper in the swath laying mode and laid down on a field in the form of a swath. In the swath laying mode, the straw guide plates are moved into a position, in which the chaff is distributed over the operating width to both sides of the swath. In the swath laying mode, the chaff and the straw are distributed on the field over the operating width. In this case, the chaff is conveyed into the straw chopper by the blower of the cleaning assembly and the suction effect of the straw chopper.
Similar arrangements are known from the prospectuses “Deutz-Fahr Topliner 8XL,” Imprint 91 532 01 Printed in Germany 9906, “Case IH Cross-Flow,” Imprint CF80-D-BR-10/99, and New Holland CX Mähdrescher, Imprint Printed in Italy——01/09—Satiz Srl (Turin)—Cod. N. 12003/BR/D00. In these arrangements, the straw is either conveyed through the straw chopper, chopped and distributed over the operating width or conveyed around the rear side of the straw chopper and laid down on the field in the form of swaths. The chaff is conveyed into the straw chopper by the blowers of the chaff spreaders (Deutz-Fahr), impeller blower chaff spreaders (Case IH) or hydraulically driven radial blowers (New Holland). Since the straw chopper also operates in the swath laying mode, the chaff is distributed over the operating width and the straw can be harvested without a chaff fraction.
One disadvantage of the combine proposed in EP 0 727 135 A can be seen in the fact that a broad distribution of the chaff is not possible in the swath laying mode. Although the embodiments disclosed in the two above-cited WO publications are able to operate in several modes due to the utilization of separate chaff spreaders, the chaff spreaders are relatively expensive and heavy. In the embodiment according to DE 100 64 356 A and the cited prospectuses, chaff spreaders are not required because this function is fulfilled by the straw chopper. However, problems in conveying the chaff can be expected in the embodiment according to DE 100 64 356 A because the chaff is exclusively conveyed into the straw chopper by the blower of the cleaning assembly and the suction effect of the straw chopper. In the embodiments proposed in the aforementioned prospectuses and in EP 0 727 135 A, the chaff is conveyed by blowers that usually operate with a relatively low degree of efficiency. The embodiments according to DE 100 64 356 A and the aforementioned prospectuses only allow a broad distribution of the chaff. However, it is also desirable to incorporate the chaff into the straw swath in certain applications.